Mold and method of casting aluminum



June .18, 1929. D, J, CAMPBELL 1,717,916

MOLD AND METHOD OF CASTING ALUMINUM Filed Aug. 15, 1927 2 Sheets-She, l

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June 18, 1929. D, CAMPBELL 1,717,916

MOLD AND METHOD OF CASTING ALUMINUM Filed Aug.I 15, 1927 2 shams-shewI 2 9 t llomeg lnuQnlor Donald d. Cqmpbell Patented' June 18,` 1929.

STATES PATENT OFFICE.

I MOLD AND METHOD' 0F CASTING ALUMINUM.

Application led- August 15, 1927. Serial No. 212,947.

This invention relates to a method of casting pistons withl aluminum heads and ca'st iron depending skirts. In the usual practice of producing pistons of this type the skirt of cast iron is heated to a high degree of temperature in order that when the melted aluminum comes in contact therewith, there shall not be a chilling of the metal and an imperfect connection made between the head and skirt of the piston. `With the method of casting Which I have devised and with the novel mold for carrying out such method it is not necessary to subject the cast metal .skirt to the heating step, it being possible with the method of my invention to 4castthe heads directly on to the skirt portions of" the piston, such skirt portion being at the beginning at normal atmospheric temperature and automatically heated and raised to desired temperature Where the aluminum contactsr\therewith during the casting of the aluminum head on said skirt.

The present invention accordingly is directed to the practical, simple and effective a method of producing a composite piston having a head of aluminum or one of its alloys and a skirt of cast iron or its alloy and in the use of a novel form of mold for effectively attaining the ends stated. r1he invention is fully described in the following description taken in connection with the accompanying drawing, in which,

' Fig. 1 isi a horiozntal section taken sub y stantially on the plane of line 1-1 of Fig. 2.

Fig. 2 is a vertical section through the mold substantially on the plane of line 2-2 of Fig. 1.

Fig.,3 is a partial side elevation and vertical section of the complete piston which is made in the mold.

Fig. l is a similar view of the skirt portion of the piston before the head is cast thereon.

Fig. 5 is a fragmentary vertical section through the mold illustrating the flow of melted aluminum to the skirt of the piston in casting the head thereon, and

Fig. 6 is a fragmentary horizontal section substantially on the plane of Iline 6-6 of Fig. 2.

Like reference characters refer to like parts in the dilerent figures vof the drawings.

In carrying out the method or processof casting aluminum heads on to the cast iron skirts of pistons a flask 1 is provided in which a mold 2 is made around the piston skirts 3 lWithin which cores 4 are located. It is to be understood that in forming this mold the flask 1 is turned over from the position which 1t occupies in Fig. 2 and located against a suitable pattern plate, the cores 1 and the piston skirts 3 being located in the flask on said plate and the mold 2 of green sand made around said skirts and cores. Preferably four ot theskirts and cores described are located in a flask though it is of course evident that the numbermay be increased Without in any marner alecting the invention.

The skirts 3 at=tlieir upper ends are eX- tended inwardly and somewhat upwardly at [an angle, making a ledge 5, from the inner edge of which a vertical ring 6 extends being of less diameter than the skirt 3).V Through the ledge 5 and the ring 6 a plurality of openings 7 are made. l rllhe cores f1 at their upper l ends are reduced in'size, as indicated at 4a, so that the same are spaced short distances from the inner sides of the ring 6.

The mold in the flask 1 forms the drag of the complete mold and the cope is formed in the\flask 8. rlhe cope mold 9 Within said flask 8 is made over a suitable pattern plate and there is provided a central vertical sprue 10 throughithe mold 9 from Which branches 11 extend communicating with circular gates4 12 in the under side of thgamold 9 which surround the upper end of ch respective piston skirt. The gates l12, as shown, communil i cate with each other at contiguous sidesand are separated from the passages 11 bythe parts 13 of the cope mold around the sprue 10. 'llhe circular gates-12 communicate with the mold cavity 16 by inlet gates 15, a plurality of which are provided at intervals around the gates 12 and mold cavity 16. From the upper side of each mold cavity 16 a riser pasf sage 14 extends for the purpose'hereafter described, this riser passage extending completely through the upper part ofthe mold. rllhe mold cavity 16 is located around the upf per end 6 of the piston skirt and over'the up.-

per end 4a of the core and shapes the aluminum head which is cast on to the upper end of the skirt.

W ith the cope located over the drag as shown in Fig. 2, the melted aluminum introduced into the mold through the sprue 1() follows the various passages llthrough the gates 12 thence through the gates 15 to the upper ends of the piston skirts. The melted aluminum flows through the openings 7 around the upper end portions 4l1 of the cores 4 and finally begins to rise and fill the recesses 16 of the mold. In Fig. 5 there is shown a head in the process of casting wherein the melted aluminum has not yet reached the upper end of the projection 4 of a core. But wlth the continued progress of pouring all of the recesses and cavities of the mold will be filled with melted aluminum and it will also rise into the riser 14 which will provide a head 16a for the piston, the gates 12 being tilled with a ring 12 of aluminum connected with the head by radial members a and connected by parts 11 with a residue of melted aluminum which is in the sprue 10. The parts 15*l and the part formed in the riser 14 may be readily broken from the head leaving the piston complete and the head interlocked with the skirt 3.

It is evident that all of the metal entering the mold cavity must flow against and past the upper end of the skirt and that the continuous flow of aluminum aroundand past the ring 6 and ledge 5 of the piston skirt serves to heat the parts to a high degree of temperature and expand the same to the necessary degree of temperature before the pouring of melted aluminum is completed, and

securely that there Will be no'chilling of the aluminum because of its contact with the cold cast iron; and that any of the same which first reaches the cast iron and is momentarily chilled is immediately raised to the necessary degree of temperature as the melted aluminum continues to come into the mold. The risers 14 y permit the pouring and dovving past the ring 6 of an additional amount of metal if it is desired to bring the ring 6 to a higher temperature and the metal in the riser 14 and. in the ring 12*1 provides for shrinkage in the moldl cavity as the metal cools. lhis obviates entirely any necessity of preheating the cast iron skirts of the piston and. is a very valuable feature of the inyention.

There are numerous variations which may be resorted to in carrying out this method. 1t is not necessary to cast iour pistons at once `as this number can readily be varied, in-

creased or diminished as desired. The heads ot aluminum are inseparately connected with the skirts of cast iron and a shrinking of the iron in cooling is accompanied by a compensating shrinkage of aluminum, the iron where it engages with the aluminum having been increased to a high temperature and suiiiciently ex anded beforehardening of the aluminum egins to take place.

The term aluminum wherever it appears in this specification is to be interpreted as meaning either aluminum or any metal ot' substantially equivalent characteristics and the term is not to be held to its strictest sense inasmuch as various aluminum alloys and possibly entirely different metals may be used in the place of but for the same purpose as aluminum described herein.

The invention is del'ined in the appended claims and eomprehends all matters defined in and coming within the scope thereof.

1. The method of producing a composite piston of aluminum and cast iron which conf sists in casting a head of aluminum on to the upper end of a skirt of cast iron, and in flowing all of the molten metalfor said head around and over the upperend of said skirt, whereby the up )er end ofthe skirt is raised to a high degree ol temperature duri-ng the time that the molten metal ffor said head is being entered into the mold. y

2. A mold comprising, a drag having a piston skirt embedded therein, the upper end of the skirt extending above the upper side of vthe drag, a core within the skirt, the upper ',end thereof being of less diameter than the inner diameter of the upper end of the skirt and extending above the upper end of the said skirt, a cope located over the drag having a recess for the head of the piston located over and around the upper ends of said skirt and core, said cope being formed at its under side with a circular groove around said recess therein and with a plurality of spaced apart gates extending from said groove connecting said groove with said recess.

3. A mold comprising, a drag having a piston skirt embedded therein, the upper end of the skirt extending above the upper side of the drag, a core located within the skirt having its upper end extending above the-u perv end of the skirt, a cope located over the ra having a cylindrical recess above and aroun the upper ends of said skirt and core, and

passages at the under side of said cope be- A tween4 it and the drag for conducting molten :metal into said recess at the lower end thereof around said upper end of the skirt and core.

4. A mold comprising, a drag having a iston skirt embedded therein, the upper en of the skirt extending above the upper side of Vthe drag, a core Within said skirt having an upper end portion of reduced size so that its sides are spaced from the inner sides of the upper end of said skirt, a cope located over the drag having a cylindrical recess around and over the upper ends of said skirt and core,`

said cope at its under side having a circular groove therein around the lower end of said recess and spaced a short distance therefrom, with connecting gate passages leading from said groove into said recess whereby molten metal poured into the mold and conducted to said groove lows through said gates into the recess at its lower end at a plurality of spaced apart points.

5. A mold for casting aluminum heads onto iron skirts of pistons, having a mold cavity to shape the aluminum head, the iron skirt v lit) being embedded in the mold with an end projecting into said mold cavity, said mold also having a pouring passage and communicating passages therefrom leading into the mold cavity at points adjacent the end of the skirt therein, whereby molten aluminum entering the mold cavity must pass by and against the said end of the skirt.

6. A mold for casting aluminum heads onto iron skirts of pistons, having a mold cavity to form said head, an iron skirt embedded in the mold and having an end extending into said mold cavity., said mold also having an annular gate surrounding the mold cavity, a pouring passage communicating with said annular gate and a plurality of entrance passages rom said annular gate entering said mold cavity at points adjacent said projecting end of the iron skirt whereby molten aluminum entering said mold cavity must pass by and against said projecting end orq the skirt. p

7. A mold for casting aluminum heads onto iron skirts of pistons, having a mold cavity, an iron skirt embedded in the mold and having an end projecting into said mold cavity, the mold also having a pouring passage, a plurality of entrance passages communicating therewithpand entering the mold cavity at points adjacent the said projecting end of the skirt and a riser passage extending from `the upper side of the mold cavity whereby molten aluminum entering the mold cavity must pass by and against the said projecting ends of the skirt and a surplus amount of metal may be passed through the mold cavity and into said riser assage.

8. A. mold for castlng aluminum heads onto iron skirts of pistons, having a mold cavity, having an end extending into said mold cav- Ity, the surrounding the mold cavity, a pouring passage communicating With said annular gate, a plurality of entrance passages from said annular gate entering said mold cavity at points adjacent said projecting end of the iron skirt and a riser passage extending from the upper side of the mold cavity, whereby molten aluminum ventering the mold cavity must flow by and against the projecting end' ot the skirt and a surplus amount of aluminum may be flowed into the mold cavity and into said riser passage. i v 0 9. mold for making composite castings', having a mold cavity to shape one portion of l said casting, the other portion of said casting being embedded in the mold with a part projecting into said mold cavity, said mold also having a passage leading into the mold cavity at a point adjacent the part of 'the casting extending into the cavity whereby molten metal entering the mold cavity must pass by and against the said part of the castingf ln testimony whereof I afix my signature.

' DONALD J. CAMPBELL.

an iron skirt embedded in the mold and mold also having an annular gatev 

